Mimic's Sister - Shapeshifter

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stinkyrob:
I've been following this for a long time, and am still in awe. Your skills and attention to detail rock my socks. I look forward to more updates!

Arroyo:
Looking good as usual Laythe, keep it comin.

Laythe:
I've made some more progress.

Spent a while working on one of the virtual pinball toys. There is traditionally a loud knocker that fires when you win a free game. This is often a solenoid whacking the inside of the plywood cabinet directly, using the whole cabinet as a giant sounding box - but I don't exactly have a solid box cabinet like a traditional pinball machine does, so I improvised a bit.

I found a relatively powerful 120vac solenoid, and mounted it to a small wooden subframe. Cut a chunk of thick-wall stainless steel rectangular tube, bored a hole in one side of it for the solenoid striker to reach through the tube and strike the far side wall of. Drilled it, tapped it, and screwed it tight to the face of the solenoid. Mounted a very light spring to a cross pin on the moving plunger in tension to reset it.

Here's the result.

When the coil is charged from a very brief (10 millisecond) shot of 120v across a relay, the |-|> shape at the right of the solenoid tries to become ||>, but just slightly before the plates touch, the plunger inside strikes the far end of the stainless tubing with a good loud crack. Then the spring pulls it back into this resting configuration.

This lives on the midshelf up near the rear cabinet. Of course, when I went to test it, I then couldn't win a free game to save my life. ::)

(Eventually managed to. It works great.)

Current working pinball toy count:

* 5 RGB flashers between backbox monitors
* 4 white LED strobes, two behind backbox, two under front cabinet
* Left and right flipper contactors mounted directly to the flipper buttons
* Left and right slingshot contactors, mounted against the side skirts further ahead
* Bumper solenoid mounted well up the midshelf, mapped to "Center" and "Back" bumper events
* Replay knocker mounted at the back end of the midshelf
Next work is on a minor ergonomic problem that has plagued the design. When it's in pinball mode, if you put your thumbs up past the lockdown bar on the tops of what would be the side rails of a real pinball machine, you can flex the table back and forth a bit. You're actually flexing the spring rod that cushions the television against the abrupt start and stop of the actuator that rotates it - that is all, by design, not a rigid structure on purpose.

I wasn't sure how bad it would be in practice, given most of your palms weight is on the lockdown bar, not the side rails, and the centerline of the flipper buttons goes right about exactly through the axle.

It was flexible enough to be annoying, it didn't feel right.

So, I've made a fix for that.

First up, a block of steel. Mild steel this time, not stainless. I hate having anything on Shapeshifter that can rust, so this is a steel block under about four layers of rustoleum flat black. Four countersunk screw holes in the corners for mounting.

This gets screwed down to the top of the midshelf, right behind the front cabinet. This is the view looking down just behind the lockdown bar, from the pinball player position, with the playfield monitor up in vertical driving mode. Four screws clamp this block down.

This block will be one side of a strong magnetic latch. I can only do this on the left side, where the playfield rotates away from it, because the right side has to swing through anything below it. This is going to catch the giant aluminum bracket you see on the right, which also mounts the fronts of the skirts. I've drawn a dot on this bracket where the magnet should mount to hit the middle of this steel block.

I'm doing all work from here on without disassembling the machine, so setting the magnet end requires drilling aluminum in situ.

I took some now-no-longer-needed engineering drawings from making other parts of the machine, and masking taped them up to form a dam to keep aluminum shavings out of the rest of the electronics.

Used a hand drill with a number 36 bit in it, to laboriously peck drill a 1.25" deep hole into the bracket.

This took me a long time. If you're playing the home game and building along, you should measure this out and do it in a drill press before you mount the whole thing together. Me, I did it over the course of about 45 minutes wishing I could be using my drill press.

Once it's drilled to depth, then I tapped it 6-32.

Pro tip: Don't break off a tap in the assembled machine.

Wisely, I didn't break off a tap in the assembled machine.

This gets a 95-pound-rated cup magnet on a countersunk 6-32 screw with a lock washer and a nut to pin the magnet hard against the countersink, then a reversed nylock nut to act as a jam nut up against the aluminum threaded bracket, then about an inch of 6-32 threads to be nice and strong in the bracket.

Here's the magnet assembly just started into the threads:

This acts like a leg leveller foot on an arcade machine, only the end of it is a strong magnet. (It screws in until the nut touches the bracket.)

This is tunable in a lot of ways. You can space whatever amount of nonferrous material between the steel and the magnet to adjust the strength of the latch, you can screw the magnet in and out of the bracket to tune the exact stop angle to make the pinball table land EXACTLY flat to the backbox... and you can make the spacer material hard or resilient to compromise shock absorption versus residual flexibility of the pinball table.

The winning compromise ended up being one layer of a black silicone placemat, which I trimmed to fit overlength and screwed down over the steel block.

End result: You can't tip the pinball table left at all, because to do that you'd be shoving the magnet through the steel block. That side is very strong. You can't tip the pinball table right until you push hard enough to pop the magnet up off the steel block - which is a lot of force, not something you do at all by accident.

When the actuator shoves the monitor into driving mode, it's strong enough to pop it right off the block, it's got about 20lb of force behind it. The twisting load to pop it loose is all between the actuator rod to the TV tray brackets, to the thick axle tube, to the front skirt bracket - none of that goes through the monitor.

I'm happy with how it works, and now pinball mode feels decently solid even if you get a little excited playing. Not quite as rock solid as a full box would be, but, there's some compromises to the crazy thing I'm doing here and it's no longer distressingly flexible. It's pretty good now, I consider the problem solved.

Still to do:

* Limit switches, so the software can be aware of the status of the moving parts, which I'm going to do before I set the software to full automatic transformation, to guard against anything going wrong mid-transform.
* Disassemble the side skirts again, cut relief for the angle aluminum to inlet them into the corner, bodywork, prime, paint very very red, polish, glue aluminum fake siderails on, reassemble everything
* Software tweaking and tuning, to include full automatic transformation
* Throw a party to let my friends come over and see it and play it

Laythe:
I got that magnet latch tuned just right, the pinball table now rests dead level. Here's where it really lives, so you can see how deep the threads go.

There's a lot of threads into the aluminum, so I trust that.

Here's the machine parked on the latch, in pinball mode...

Sadly, the last time it is to be together and playable for a while, because Progress Must Be Made.

You can see the side skirts that bear the pinball flipper buttons are bare plywood. They are going to be the next thing on the list.

Upon seeing the machine together, and that the side skirts run pretty much flush with the sides of the front and rear cabinet, I've decided that the aluminum angle fake side rails I'm going to make should be flush, not lapped over - this should both look better, and improve their clearance when the table rotates, because those corners get mighty close to the control panel rails and the tail of the control panel as they go by.

First up, disassembly.

The side skirts come off.

The slingshot contactors mount to the side skirts between the front and rear mounts, so they come off too.

To do the inletting for the aluminum angle to sink it flush, I know most of you all would use a router. As shown by this project so far though, I'm not much of a router guy - this says tablesaw to me.

Before disassembly, I traced a line onto the skirts at where the aluminum, set against the playfield monitor bezel, ends on the side skirts.

I made a sequence of shallow passes, adjusting the fence about 3/4ths of a kerf at a time, to approach that line...

The bottom of the cut is of course ribbed because of the saw's tooth profile, but it's going to get filled with construction adhesive when I glue the fake side rails into it, so that's no bad thing.

I got to the line on both pieces - here are the skirts ready for the first pass of filler.

Skim filled, sanded, skim filled, sanded, and they shape up like this -

Then the first coat of primer goes on them.

That brings us up to the present; I'll certainly be doing at least one more coat of primer, possibly two, depending on how much building up and sanding down it takes for me to be happy with the surface.

This is, I think, the last body work that has to happen on the whole of Shapeshifter. It's less of a chore when it's the home stretch. I'll want to get a really thick coat of red on these, because the area around the pinball flipper buttons will be the first place it wears through from use, that's the heaviest contact area.

I'm trying to see that as an okay outcome - I think actual pinball machines tend to show the same kind of wear, so it will just be a touch of authenticity.

javeryh:
I just can't get over the level of detail in this project. I am truly in awe every time you update this thread. :cheers:

I've never even messed around with virtual pinball before - where would be a good place to start? Is there one program like MAME that you can play all the tables on?

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